The Foot. 395 



point it sweeps across the sole to the inner border to join 

 the dorsal incision, lying, in its course, just behind the 

 heads of the metatarsal bones. It must be remembered 

 that the joints between the tarsal and the metatarsal bones 

 are not in the same plane, since the joint between the 

 first metatarsal and the internal cuneiform is half an inch 

 in front of the joint between the second metatarsal and the 

 middle cuneiform, and that this latter joint is one-quarter 

 of an inch behind the joint between the third metatarsal 

 and the external cuneiform ; and further, that, in this 

 operation, after the dorsal ligaments binding the metatar- 

 sal to the tarsal bones have been divided, it will be neces- 

 sary to insert the knife, held like a trocar, between the 

 bases of the first and second metatarsal bones and then to 

 elevate the handle until it is perpendicular to the dorsum 

 of the foot so as to divide the strong ligament of Lisfranc. 

 Choparfs Operation. The dorsal incision in this 

 operation commences at a point about midway between 

 the external malleolus and the tuberosity of the fifth meta- 

 tarsal bone, and crosses the bases of the metatarsal bones 

 to a point just behind the tuberosity of the scaphoid on 

 the inner side of the foot. The plantar flap follows the 

 main lines of Lis franc's operation, but crosses the sole 

 about the middle of the metatarsus. In this operation the 

 bones are disarticulated at the medio-tarsal joint, which is 

 composed of two articulations, viz., the caleaneo-cuboid on 

 the outer side, and the astragalo-scaphoid on the inner. 

 These two joints have distinct synovial membranes and 

 lie almost in a transverse line, the astragalo-scaphoid, 

 however, being convex anteriorly, and the calcaneo-cuboid 

 somewhat concave anteriorly, the two somewhat resem- 

 bling the letter /. If this shape of the medio-tarsal joint 

 be not kept in mind, some difficulty may be encountered 

 in the disarticulation. 



